Imagine if the presidential candidates were willing to talk frankly about the things that affect us most: not just guns and butter, but also life and death and the hard choices our next President will have to help us make. It would be a revealing debate, with questions like these:

For Barack Obama: Democrats have long argued for greater reproductive freedom. Do you think that should include the right to choose the sex of your child? The same genetic tests that screen for terrible diseases could in theory target many other predispositions. What if prospective parents could screen for short or...